The March 28,2025 Myanmar earthquake generated ground shaking that was perceptible throughout Myanmar and adjacent regions.This study simulated three-component ground motions across the affected region using an improv...The March 28,2025 Myanmar earthquake generated ground shaking that was perceptible throughout Myanmar and adjacent regions.This study simulated three-component ground motions across the affected region using an improved stochastic finite-fault method to systematically assess seismic impacts.Observed near-field recordings at MM.NGU station was used to determine the reliability of the theoretically derived stress drop as input for simulation.Far-field recordings constrained the frequency-dependent S-wave quality factors(Q(f)=283.305f^(0.588))for anelastic attenuation modeling.Comparisons of peak accelerations between simulation and empirical ground-motion models showed good agreement at moderate-to-large distances.However,lower near-fault simulations indicate a weaker-than-average source effect.Analysis of simulated instrumental seismic intensity revealed key patterns.Maximum intensity(Ⅹ)occurred in isolated patches within the ruptured fault projection,correlating with shallow high-slip areas.TheⅨ-intensity zone formed a north-south elongated band centered on fault projection.Significant asymmetry inⅧ-intensity distribution perpendicular to the fault strike was observed,with a wider western extension attributed to lower shear-wave velocities west of the fault.Supershear rupture behavior enhanced ground motions,expanding intensity ranges by~20%compared to sub-shear rupture.This study reveals the integrated effects of fault geometry,slip spatial distribution,rupture velocity,and site condition in governing ground motion patterns.展开更多
A great earthquake struck central Myanmar on March 28,2025,causing extensive and severe damage in Myanmar and neighboring countries such as Thailand.Observed waveforms indicated the possibility of supershear rupture a...A great earthquake struck central Myanmar on March 28,2025,causing extensive and severe damage in Myanmar and neighboring countries such as Thailand.Observed waveforms indicated the possibility of supershear rupture at the source of this event.To investigate this possibility,a joint source inversion using near-field and teleseismic waveforms was performed.The fault model used,with a total length of 580 km,comprises five segments with varying strike directions and dip angles.Within the first 10 s after initiation at the hypocenter,the rupture propagated southward at a high speed of 5–6 km/s.while rupture in the northern direction proceeded at a speed lower than the local S-wave velocity of 3.5 km/s.Subsequently,the rupture propagated bilaterally in both northern and southern directions at high speeds of 5–6 km/s.The largest asperity,with a maximum slip of 5–6 m,occurred in the shallow part of the fault model,approximately 240 km south of the hypocenter.Large slips of 2–3 m were also found near the southern end of the fault model.Slips on the fault plane were dominated by strike-slip components,though slips south of the largest asperity included significant dip-slip components.展开更多
基金National Key R&D Program of China under Grant No.2022YFC3003601。
文摘The March 28,2025 Myanmar earthquake generated ground shaking that was perceptible throughout Myanmar and adjacent regions.This study simulated three-component ground motions across the affected region using an improved stochastic finite-fault method to systematically assess seismic impacts.Observed near-field recordings at MM.NGU station was used to determine the reliability of the theoretically derived stress drop as input for simulation.Far-field recordings constrained the frequency-dependent S-wave quality factors(Q(f)=283.305f^(0.588))for anelastic attenuation modeling.Comparisons of peak accelerations between simulation and empirical ground-motion models showed good agreement at moderate-to-large distances.However,lower near-fault simulations indicate a weaker-than-average source effect.Analysis of simulated instrumental seismic intensity revealed key patterns.Maximum intensity(Ⅹ)occurred in isolated patches within the ruptured fault projection,correlating with shallow high-slip areas.TheⅨ-intensity zone formed a north-south elongated band centered on fault projection.Significant asymmetry inⅧ-intensity distribution perpendicular to the fault strike was observed,with a wider western extension attributed to lower shear-wave velocities west of the fault.Supershear rupture behavior enhanced ground motions,expanding intensity ranges by~20%compared to sub-shear rupture.This study reveals the integrated effects of fault geometry,slip spatial distribution,rupture velocity,and site condition in governing ground motion patterns.
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant No.2024B15National Natural Science Fundation of China under Grant Nos.U2239252 and 52478567Natural Science Foundation of Heilongjiang Province under Grant No.JQ2023E002。
文摘A great earthquake struck central Myanmar on March 28,2025,causing extensive and severe damage in Myanmar and neighboring countries such as Thailand.Observed waveforms indicated the possibility of supershear rupture at the source of this event.To investigate this possibility,a joint source inversion using near-field and teleseismic waveforms was performed.The fault model used,with a total length of 580 km,comprises five segments with varying strike directions and dip angles.Within the first 10 s after initiation at the hypocenter,the rupture propagated southward at a high speed of 5–6 km/s.while rupture in the northern direction proceeded at a speed lower than the local S-wave velocity of 3.5 km/s.Subsequently,the rupture propagated bilaterally in both northern and southern directions at high speeds of 5–6 km/s.The largest asperity,with a maximum slip of 5–6 m,occurred in the shallow part of the fault model,approximately 240 km south of the hypocenter.Large slips of 2–3 m were also found near the southern end of the fault model.Slips on the fault plane were dominated by strike-slip components,though slips south of the largest asperity included significant dip-slip components.
